Lime metering or feeding devices are used for adding lime to streams of water in proportion to the amount of water flowing in such streams. Examples of such devices are given in Swedish patent No. 7904599-6 and in Swedish patent application No. 8503000-5. Due to their construction, these devices must be made comparatively large to become economical, and they also require that a comparatively finely ground lime be used in order to ensure that it will be dissolved. Alternatively, cost increasing measures must be taken, to provide lime traps and the like.